body, html {
	margin: 0;
	height: 100%;
	background: #FFF;
	background-size: 100% 100%;
}

.center {
	margin: 0;
	position: absolute;
	top: 50%;
	left: 50%;
	-ms-transform: translate(-50%, -50%);
	transform: translate(-50%, -50%);
}

.contain, .stretch, .cover {
	display: block;
	width: 100%;
	height: 100%;
}
.contain { object-fit: contain; }
.cover { object-fit: cover; }

/* 支持暗色主题后，取消注释这一段

@media (prefers-color-scheme: dark) {
	body {
		color: white;
		background-color: #000;
	}
}

*/